The present invention relates to a ferroelectric memory, a semiconductor device, a method of manufacturing a ferroelectric memory, and a method of manufacturing a semiconductor device.
A ferroelectric memory (FeRAM) retains data by spontaneous polarization of a ferroelectric capacitor using a ferroelectric thin film. In recent years, a semiconductor device using such a ferroelectric memory has attracted attention.
In the field of ferroelectric memory, one factor which determines characteristics of the device is the crystallization state of the ferroelectric thin film included in the ferroelectric capacitor. The manufacturing steps of the ferroelectric memory include a step of forming an interlayer dielectric or a protective film, in which a process which causes a large amount of hydrogen to be generated is used. Since the ferroelectric thin film is formed by using a ferroelectric which is generally formed of an oxide, the oxide may be reduced by hydrogen generated during the manufacturing step and adversely affect the characteristics of the ferroelectric capacitor.
As a method for improving the characteristics of the ferroelectric capacitor affected by hydrogen, a method of recovering the crystallization state of the ferroelectric thin film by using a high-temperature heat treatment using an electric kiln or the like can be given. However, this method may affect the characteristics of peripheral members such as metal interconnects in a state in which an interlayer dielectric or a protective film is formed due to atom diffusion or the like. In the case of integrating other semiconductor devices such as transistors in the ferroelectric memory, characteristics of the transistors may be adversely affected due to a thermal load applied during the high-temperature heat treatment. Therefore, a technology capable of recovering the characteristics of the ferroelectric capacitor while reducing the thermal load applied to the device has been demanded.